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Healthy volunteers who received LSD, ketamine or psilocybin, a compound found in magic mushrooms, were found to have more random brain activity than normal while under the influence, according to a study into the effects of the drugs.

Researchers at the University of Sussex and Imperial College, London, measured the activity of neurons in people’s brains as the drugs took hold. Similar measurements have shown that when people are asleep or under anaesthetic, their neurons tend to fire in a more predictable way than when they are awake.

“What we find is that under each of these psychedelic compounds, this specific measure of global conscious level goes up, so it moves in the other direction. The neural activity becomes more unpredictable,” said Anil Seth, a professor of neuroscience at the University of Sussex. “Until now, we’ve only ever seen decreases compared to the baseline of the normal waking state.”

The research, published in the journal Scientific Reports, appears 74 years to the day after the Swiss chemist Albert Hoffman went on the world’s first LSD trip.

After the Guardian article just gets into a long expose of Hoffman's experience. But it does seem to identify one of the authors a bit later on:

Robin Carhart-Harris, a researcher at Imperial College who took part in the study, said the sudden increase in randomness in brain activity appeared to reflect a deeper and richer conscious state.

“People tend to associate phrases like ‘a higher state of consciousness’ with hippy speak and mystical nonsense. This is potentially the beginning of the demystification, showing its physiological and biological underpinnings,” he said. “Maybe this is a neural signature of the mind opening.”